Heat exchangers are known where straight heat exchanger tubes are used and it is known to insert such tubes automatically.
British patent specification 2 157 985 shows a system for threading U-shaped tubes into a heat exchanger core, but this requires the use of lacing rods which are introduced from below through the holes in the core, and which guide the leading ends of the U-shaped tubes. This is shown in FIGS. 10, 11, 12 and 13 of British patent specification 2 157 985.
European patent specification 0 126 457 also describes a system for inserting U-shaped tubes into a heat exchanger, but in this case the tubes are moved horizontally into holes in the heat exchanger, and are merely supported from below during the insertion process.